BACKGROUND: Different anesthetic techniques have been used for fast tracking in cardiac anesthesia. Remifentanil, with its unique pharmacokinetic profile, could be an ideal drug for fast tracking. Possible limitations of remifentanil are rapid onset of postoperative pain after discontinuation of the drug infusion, which may increase the risk of an ischemic event. We conducted this randomized study to compare the efficacy of remifentanil versus low doses of fentanyl in fast-track cardiac anesthesia. It has been hypothesized that remifentanil would provide a safe anesthesia with no impact on myocardial function and with positive effects on extubation time and mobilization. METHODS: We compared the postoperative course of patients, the remifentanil group (RG) and the low-dose fentanyl group (LDFG), in whom remifentanil and low-dose fentanyl, respectively, were used for fast-track cardiac anesthesia. The study was designed as a prospective randomized study. The primary outcomes were changes in the cardiac index and creatine kinase MB fraction (CKMB), extubation times, mobilization times, and lengths of stay in the intensive care unit (ICU) and the hospital. Frequency of myocardial infarction (MI), reoperations due to excessive bleeding, renal impairment, and cerebral complications were registered as well. RESULTS: Seventy-one patients were enrolled in the study, and 7 were excluded due to difficult airway, bleeding, and technical difficulties. The RG comprised 33 patients and the LDFG comprised of 31 patients. There were no differences between the groups in terms of age, Euroscore, types of surgery, extracorporeal circulation, and aortic cross-clamp time. We did not find significant difference in cardiac index, CKMB, extubation times, mobilization times, length of stay in the ICU and in the hospital between the groups. Postoperative complications such as MI, rates of reoperations, renal and cerebral complications and incidence of atrial fibrillation did not show any significant differences. CONCLUSIONS: Remifentanil fast-track anesthesia for cardiac patients has no negative impact on myocardial function. Both remifentanil and low-dose fentanyl are equally effective and safe for fast-track cardiac anesthesia. The study did not highlight any statistical superiority of remifentanil anesthesia over low-dose fentanyl anesthesia.